1. Field of the Invention
The present invention relates to alpine ski boots. In particular, it relates to ski boot structure improvements to facilitate the comfort, safety and wearability of the ski boots both on and off the skis.
2. Description of Related Art
Presently, ski boots for alpine skiing are generally of a construction having a hard plastic upper and a rigid boot sole. Despite several disadvantages boots with hard plastic uppers are the standard for alpine skiers. This standard evolved for several reasons.
Alpine ski boots require a rigid boot sole to cooperate properly with modern quick-release bindings. These spring loaded bindings allow a user to easily attach a ski by placing the toe of a booted foot into the automatic binding and stepping down on the boot heel to lock the boot to the ski. The boot is easily released from the binding by a trigger mechanism selectively activated by the user with a pole or an opposite foot. The quick-release bindings also function automatically at a predetermined setting to release the rigid boot sole in extraordinary loading situations, such as in an accident. Release of the rigid boot sole in an accident allows the skier to separate from the ski, thus preventing the ski from injuring the skier.
However, in order to properly interact with the binding for entry and release manually or automatically, the boot sole must be completely rigid from heel to toe. The binding firmly clamps the rigid boot sole to the ski, so that, under ordinary skiing conditions, the skier's foot in the ski boot is held firmly with respect to the ski attached to the binding. The firm hold of the skier's foot with respect to the ski is essential to facilitate the skier's ability to control the orientation of the skis, and thereby, to safely control the direction and speed of travel on mountain slopes.
Hard plastic uppers are said to prevent the lower leg and ankle injuries common to skiers using an earlier style of boot and binding, namely leather boots with fixed bindings.
Hard plastic uppers are also said to provide a rigid link-up between a skier's foot and leg, which allows the skier to properly shift and direct body weight to the skis to effect a turn. Conventionally shaped skis with substantially parallel sides are biased towards travel in a straight line, and resist turning. Parallel sided skis therefore require a weight shift towards the front of the ski (i.e., "forward loading") to bend the forward part of the ski sufficiently to induce the ski to carve a turn. Therefore, to better accomplish forward loading, hard plastic boots are pitched or angled forward slightly causing the skier to assume an unnatural posture with knees slightly bent.
Hard plastic boots have a number of disadvantages. Hard plastic boots are difficult to put on and take off. The hard and inflexible plastic shell requires heavy, often metal, buckles which are difficult to tighten and release. Hard plastic boots are poor insulators and are often uncomfortable in cold weather. The rigid, inflexible construction of hard plastic boots can constrict blood flow to and from the feet, causing numbness and increased susceptibility to the cold. Hard plastic boots are bulky, heavy and uncomfortable to wear both on the ski and off the ski.
Hard plastic boots are cumbersome and difficult to walk in when released from the skis. While skiing, a skier wearing hard plastic boots has enhanced control and maneuverability due to the rigid construction of the boots which firmly position the foot with respect to the ski. However, once released from the skis, hard plastic boots handicap the mobility of the wearer. Maneuvering about a ski area with the skis removed from the boots, such as, for example, maneuvering in the ski lodge, or to and from a locker or a vehicle requires extra effort and agility on the part of the wearer. The rigidity of both the sole and the uppers and the forward pitched posture of the uppers makes walking on level, dry surfaces difficult, while traversing staircases is particularly hazardous. The slippery conditions caused by ice, melting snow and mud commonly found both outside and inside ski facilities certainly compound the maneuverability problems associated with hard plastic ski boots, and may result in dangerous falls. It is not uncommon to see skiers of various ages and skill levels in hard plastic ski boots flailing their arms in a desperate attempt to regain their balance after the boots have caused a mis-step. Driving a car in hard plastic ski boots is especially difficult and dangerous, if not impossible, due to the bulk of the boots and an almost complete lack of feel for the car's accelerator and brake pedals.
U.S. Pat. Nos. 5,026,087, 5,020,822 and 4,880,251, all to Wulf et al., disclose a ski boot having a segmented foot shell rigidly attached to a sole. The segments of the foot shell overlap in sliding engagement so that a living hinge is created in the integral sole at approximately the location of the ball of the foot within the boot. To make the sole rigid for proper engagement in a ski binding, the fulcruming of the living hinge may be eliminated by locking the overlapping segments of the foot shell together. The sole therefore derives its rigidity from the foot shell, which in turn must be rigid. As noted above, a rigid sole and a rigid foot shell are thought to be necessary for proper control of conventional parallel-sided alpine skis.
The recent introduction and rapid acceptance by skiers of easy handling skis having inwardly curved opposite side edges makes it possible to create a boot without the disadvantages of the hard plastic ski boot. These skis are generally referred to in the industry as parabolic skis or, are alternatively referred to as super-sidecut skis, shaped skis or hourglass skis. The tip, or shovel, and tail of parabolic skis are significantly wider than the waist, which is the area beneath the ski boot. The dramatic shape, or sidecut, makes carving turns easier and provides greater control in nearly all snow conditions. Parabolic skis can therefore shorten the learning curve of new skiers, and increase the maneuverability and lessen the fatigue of experienced skiers. The shaped edges of parabolic skis do not resist turning to the same degree as conventional skis, and, in fact, facilitate carving turns in snow. Thus, the forces required to control the orientation and direction of parabolic skis are much lower than the forces required to control the orientation and direction of conventional skis. As a result, boots for parabolic skis need not be as rigid as conventional hard plastic ski boots. Also, because turns are more easily accomplished on parabolic skis without the degree of weight shift required on conventional skis, the rigid link-up between the skier's foot and leg is not as necessary for proper control of the skis. The rigid supporting cuff of the boot according to the present invention is made from hard plastic to provide the same type of ankle support and rigidity found in the hard plastic uppers of conventional boots.
The present invention takes advantage of the increased maneuverability of the recently developed parabolic skis to provide improvements to alpine ski boots in comfort both on and off-ski, and in off-ski maneuverability, without sacrificing on-ski performance. The primary purpose of the boot according to the invention is for use with parabolic skis, but it could alternatively be used in conjunction with other sports gear for which it may be desirable to have a rigid sole, such as, for example, conventional parallel sided skis, snowboards, in-line skates, bicycles, etc.